That spider has a really bald ass, which tells me that it might have anger/stress issues. Big hairy spiders like those sometimes like to pull out their ass hairs and throw them when they get angry/stress (or feel threatened).

Their ass hair is designed to be effective as an irritant, so some large hairy spiders will pull out their ass hairs to throw at the face of a predator to try to irritate their eyes/noses and give the spider a chance to get away.